1. Field of the Invention
The present invention relates to an air cleaner for an internal combustion engine and, more particularly, to an air cleaner for an internal combustion engine, to be used in combination with a carburetor.
2. Description of the Related Art
Referring to FIG. 9 showing an ordinary air cleaner disposed above a carburetor 115 included in an internal combustion engine, the air cleaner has an air cleaner element 100 (hereinafter referred to simply as xe2x80x9ccleaner elementxe2x80x9d) for filtering air, and an air cleaner case 101 containing the cleaner element 100. The air cleaner case 101 includes a cover 104 having a top wall 103, and a bottom wall 105. The top wall 103 of the cover 104, a top plate 110 included in the cleaner element 100, and the bottom wall 105 are fastened together by a bolt 106 set upright on a central part of the bottom wall 105 and extending through the cleaner element 100 and the top wall 103, and a nut 107 screwed on the bolt 106. An air outlet pipe 112 is formed integrally with the bottom wall 105 so as to open downward. An L-shaped connecting pipe 113 connects the air outlet pipe 112 to the air inlet of the carburetor 115. An air inlet pipe 116 is formed integrally with the cover 104 so as to project outward from the side wall of the cover 104. An intake duct 120 is connected to the air inlet pipe 116. The open free end, not shown, of the intake duct 120 is located in a space where air scarcely contaminated with dust and water can be taken in.
The cleaner element 100 has a generally annular shape. A clean air chamber surrounded by the cleaner element 100 is connected to the air outlet pipe 112. An annular space around the cleaner element 100 is connected to the air inlet pipe 116. The top wall 103 of the cover 104 has a flat upper surface to prevent dust and water from staying on the top wall 103. An internal engine provided with an air cleaner disposed above a carburetor as shown in FIG. 9 is disclosed in JU-A No. 5-10772.
The air cleaner shown in FIG. 9 has the following problems.
(1) Work for removing the cover 104 when cleaning or replacing the cleaner element 100 is troublesome because the intake duct 120 must be disconnected from the cover 104.
(2) The position of the open free end of the intake duct 120 may be changed according to a type of a work machine or apparatus mounted with the internal combustion engine and, in some cases, the position of the air inlet pipe 116 is changed. However, since the trade name, the manufacturer""s name, specifications and the like are often indicated on the top wall 103 of the cover 104, the direction of letters printed on the top wall 103 deviates from a desired direction when the cover 104 is turned about the axis of the bolt 106 to change the position of the air intake pipe 116.
(3) Since the top wall 103 has a flat upper surface to prevent dust and water from staying thereon, the nut 107 protrudes upward from the upper surface of the top wall 103 and, consequently, the overall height of the internal combustion engine increases. If it is desired to reduce the overall height of the internal combustion engine, the capacity of the air cleaner must be reduced. It is possible to secure a desired capacity of the air cleaner without increasing the overall height of the internal combustion engine by forming a depression 102 as indicated by imaginary lines in a central part of the top wall 103 so that the nut 107 sinks in the depression 102. However, dust and water will stay in the depression 102, the water and dust staying in the depression 102 spoil the appearance of the air cleaner and corrode the bolt 106 and the nut 107. Consequently, the nut 107 cannot be easily removed from the bolt 106, which makes the removal of the cover 104 difficult. It is possible that the water or dust collected in the depression 102 will drop through the central hole of the top wall 103 and will adhere to the cleaner element 100 when removing the cover 104.
(4) The air cleaner case 101 disposed above the carburetor 115 makes difficult the adjustment of a fuel flow adjusting screw 130, such as an idle adjusting screw. A large space must be formed around the fuel flow adjusting screw 130 and it is difficult to dispose the air cleaner close to the carburetor 115.
The present invention has been made to solve the foregoing problems and it is therefore an object of the present invention to provide a compact air cleaner for an internal combustion engine, facilitating maintenance work thereof.
Another object of the present invention is to provide an air cleaner facilitating work for adjusting a carburetor disposed under the air cleaner.
According to a first aspect of the present invention, an air cleaner for an internal combustion engine, combined with a carburetor comprises a cleaner element for cleaning air; and an air cleaner case holding the cleaner element therein; wherein the air cleaner case includes a body having a pair of opposite open ends and provided with an air inlet, a base wall capable of detachably joined to one of the open ends of the body and provided with an air outlet connected to the carburetor, and a cover detachably joined to the other open end of the body.
In the air cleaner according to the first aspect of the present invention, it is preferable that the cover of the air cleaner case is detachably joined to the body by a screw-type fastening means, the cover has a concave part defining a space for receiving the head of a screw or a nut included in the screw-type fastening means, and drain holes are formed in the concave part to drain water collected in the concave part. Preferably the base wall is provided in its central part with a tubular wall projecting toward the concave part of the cover, and the drain holes are positioned inside the tubular wall. Preferably, the air cleaner case is disposed above the carburetor with the drain holes formed in the concave part of the cover located substantially right above fuel flow adjusting screws included in the carburetor, and a screw operating tool inserted from above the cover in each of the drain holes are able to reach each of the fuel flow adjusting screws.
According to a second aspect of the present invention, an air cleaner for an internal combustion engine, combined with a carburetor comprises a cleaner element for cleaning air; and an air cleaner case holding the cleaner element therein; wherein the air cleaner case includes a body, and a cover detachably joined to the body by a screw-type fastening means, the cover has a concave part defining a space for receiving the head of a screw or a nut included in the screw-type fastening means, and drain holes are formed in the concave part to drain water collected in the concave part.
In the air cleaner according to the second aspect of the present invention, it is preferable that the air cleaner case is provided in its central part with a tubular wall projecting toward the concave part of the cover, and the drain holes are positioned inside the tubular wall. Preferably, the air cleaner case is disposed above the carburetor with the drain holes formed in the concave part of the cover being located substantially right above fuel flow adjusting screws included in the carburetor, and a screw operating tool inserted from above the cover in each of the drain holes are able to reach each of the fuel flow adjusting screws.
According to the first aspect of the present invention, the air cleaner case holding the cleaner element therein is a three-part structure including the body having the pair of opposite open ends and provided with the air inlet, the base wall capable of detachably joined to one of the open ends of the body and provided with the air outlet connected to the carburetor, and the cover detachably joined to the other open end of the body. Therefore, the interior of the air cleaner can be inspected, and the cleaner element can be cleaned or replaced, by removing the cover without removing the body, so that the maintenance work can be easily carried out. Also, the position of the air inlet can be changed by turning or inverting only the body to change the position of the body without changing the position of the cover and the base wall on the side of the carburetor. Thus, the air inlet can be placed at a proper position even when the air cleaner is used in various work machines and apparatuses that take in air into the air cleaner from different spaces. Since the position of the cover does not need to be changed, the initial position and direction of letters indicating manufacturer""s name, instructions and the like printed on the cover can be maintained.
According to the first and the second aspect of the present invention, the cover of the air cleaner case has the concave part defining the space for receiving the head of the screw or the nut included in the screw-type fastening means, and the drain holes are formed in the concave part to drain water collected in the concave part. Therefore, the air cleaner having a desired capacity can be formed without increasing the overall height of the internal combustion engine, because the air cleaner can secure a sufficient air passage area without increasing the height thereof. Further, since the cover is provided with the drain holes, water is unable to stay in the concave part of the cover. Thus, dust collected in the concave part can be easily removed through the drain holes by cleaning the concave part with water. Since dust and water are unable to collect in the concave part, the air cleaner can be maintained in a satisfactory appearance, fastening means including a bolt and a nut are prevented from rusting and seizing.
According to the first and the second aspect of the present invention, the air cleaner is provided with the tubular wall projecting from the central part of the base wall toward the concave part of the cover and the drain holes are positioned inside the tubular wall. Therefore, the contamination of the cleaner element with dust and water can be effectively prevented.
According to the first and the second aspect of the present invention, the air cleaner case is disposed above the carburetor with the drain holes formed in the concave part of the cover being located substantially right above the fuel flow adjusting screws included in the carburetor, and a screw operating tool inserted from above the cover in each of the drain holes is able to reach each of the fuel flow adjusting screws. Therefore, the drain holes formed in the concave part of the cover can be used as access holes through which the screw operating tool gains access to the fuel flow adjusting screw, and hence fuel flow adjusting work for adjusting the fuel flow adjusting screw of the carburetor disposed below the air cleaner can be easily carried out.